This invention relates principally to a metal oven, furnace or kiln (collectively “furnace”), and more particularly to a unique float sled for the movement of heavy components removably attached to such furnace.
Some furnaces that supply molten metal for casting and other procedures utilize a regenerative configuration to improve efficiency. The typical regenerative furnace includes an enclosure having a hearth at its bottom for containing a molten metal, which is often aluminum. At one end of the furnace are two ports located above the hearth. These ports are connected to burner assemblies that operate alternately for supplying hot gases to the interior of the furnace enclosure. The temperature of the hot gasses is very high and is sufficient to maintain the metal in the hearth in a molten condition.
A typical regenerative burner system comprises at least one pair of regenerative burner assemblies. Each burner assembly has a burner head and a removable media box containing a media that serves as a heat sink. The media usually take the form of ceramic alumina spheres about one-inch in diameter. Typically, the media box is constructed of heavy gage metal and together with the media can weigh upwards of 10,000 pounds. Even a small media box will be very heavy and may weigh hundreds of pounds.
Regenerative burners operate as a duel burner unit or as a pair, e.g. burner “A” and burner “B”. While burner “A” is firing, the media in its media box is releasing stored heat to the combustion air that elevates the temperature of the combustion air. The combustion air flows through the media in the media box to the burner head to mix with the gas or oil for combustion. At the same time burner “B” is being utilized as an exhaust system for the combustion hot waste gasses. An exhaust fan draws these hot waste gasses through the burner head of burner “B” and through the media in the burner “B” media box, where the hot waste gasses elevate the temperature of the media and the media bed lining. Once the exhaust gasses downstream of the media box reach a predetermined temperature, which usually takes about 40 to 60 seconds, a pair of air/exhaust duct cycling valves reverse their positions. This switches burner “A” from the burner firing into the industrial furnace to the burner exhausting out of the furnace, and simultaneously switches burner “B” from the burner exhausting to the burner firing. These air/exhaust duct cycling valves are used for switching and reversing the flow of hot gases and combustion air through the media beds.
During operation, impurities, additives and coatings that volatilize during the metal heating process in the furnace (e.g., oxidation, etc.) are picked up in the hot waste gas stream and settle out in the media boxes. As the hot waste gasses flow through the media in the media boxes of the two burner assemblies, some of the contaminants also deposit on the media. These deposits eventually clog the media. Hence, from time to time each media box is detached from the burner and taken to a remote location where the media box and the media may be cleaned and otherwise reconditioned. This is a time-consuming and difficult procedure given the size, weight and temperature of the operating media boxes and the operational temperatures of the furnace. Consequently, replacing a media box traditionally requires the use of heavy lifting equipment such as jacks and lifts. Unfortunately, in many operations the media boxes are in positions or locations that are difficult to access. While lift trucks can be used to remove and replace media boxes, the positioning and alignment of the media boxes relative to the furnace ports must be relatively precise. Lift trucks and the like are not well suited to such fine alignments and extreme care must be exercised in using a lift truck or the like, which can easily damage the media box or the furnace. Further, for some furnaces, there may be insufficient room to readily utilize a lift truck.
As will become evident in this disclosure, the present invention provides benefits over the existing art.
Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.